(MAGMAMagma) I:=[0, 108, 1407, 1851, 2407, 9768, 12340]; [n le 7 select I[n] else Self(n-1) +6*Self(n-3) -6*Self(n-4) -Self(n-6) +self(n-7): n in [1..30]]; // G. C. Greubel, May 04 2018
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(MAGMAMagma) I:=[0, 108, 1407, 1851, 2407, 9768, 12340]; [n le 7 select I[n] else Self(n-1) +6*Self(n-3) -6*Self(n-4) -Self(n-6) +self(n-7): n in [1..30]]; // G. C. Greubel, May 04 2018
_Mohamed Bouhamida (bhmd95(AT)yahoo.fr), _, Jun 03 2007
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G. C. Greubel, <a href="/A115135/b115135.txt">Table of n, a(n) for n = 1..1000</a>
a(n) = 6*a(n-3) -a(n-6) +1234 for n > 6; a(1)=0, a(2)=108, a(3)=1407, a(4)=1851, a(5)=2407, a(6)=9768.
G.f.: x*(108 +1299*x +444*x^2 -92*x^3 -433*x^4 -92*x^5) / ((1-x)*(1 -6*x^3 +x^6)).
LinearRecurrence[{1, 0, 6, -6, 0, -1, 1}, {0, 108, 1407, 1851, 2407, 9768, 12340}, 50] (* G. C. Greubel, May 04 2018 *)
(PARI) x='x+O('x^30); Vec(x*(108 +1299*x +444*x^2 -92*x^3 -433*x^4 -92*x^5)/((1-x)*(1 -6*x^3 +x^6))) \\ G. C. Greubel, May 04 2018
(MAGMA) I:=[0, 108, 1407, 1851, 2407, 9768, 12340]; [n le 7 select I[n] else Self(n-1) +6*Self(n-3) -6*Self(n-4) -Self(n-6) +self(n-7): n in [1..30]]; // G. C. Greubel, May 04 2018
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<a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,6,-6,0,-1,1).
<a href="/index/Rec">Index to sequences with entries for linear recurrences with constant coefficients</a>, signature (1,0,6,-6,0,-1,1).
<a href="/index/Rea#recLCCRec">Index to sequences with linear recurrences with constant coefficients</a>, signature (1,0,6,-6,0,-1,1).
Edited and two terms added by _Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), _, May 18 2009
editing
approved